Draft gear



June 8 ,1926.

E.'-v. LAWRENCE DRAFT GEAR File -11. 1919 2v Sheets-Sheet 1 mvsmoizATTORNEY Jun 8 1926.

- E. v. LAWRENCE DRAFT GEAR Filed June 11. 1919 2 Sheets-Sheet 2 vJNVENTOR Patented June 8, 1926.

PATENT; 'oF sFrcs,

mawnm) v. LAWRENCE, or men-swoon, NEWLJERSEY, ass idfioa me "iii iv:news maven 1SAIEIEI'J'JY'BR'AZKE (COMPANY, me, A ennu -Ramon or NEWYORK.

DRIFT GEAR.

Application mean 11., 1am; scr m scans,

invention relates to c trailers and draft gearmechanisms for uselnconnection there with. ,It has special reference .to trailers whichare adapted to be connected to and sway and other undesirable movementsof 1 the trailer relative to the truck.

There are several factors wh'ikllthztve rendered draft gear mechanisms,which have hitherto been available for the-above named purpose,relatively objectionable and 'which havematerially interfered withfthesuccessful trailer and have permittedkifnot encouraged considerable sidesway of the trailer relative to the truck and therehyYincreased thedifficulties and dangers of trailer,

operation, namely 1. The connection between and the power vehicleor'tractor' has usually been established at the rear end of the body orframe materially above the line of the axle and at a considerabledistance behind the vertical plane of the axle.

a considerable amplified movement when the vehicle turns corners ormakes other curves, or due to any inequalities of the road surface, theframe acting like a lever'arm of considerable length with its pivot atthe celltre of the rear axle. In some instancesthe action is evenfurther exaggerated,the point of pivot being the centre of the frontaxle and the back Wheels the point of application of the moving force,as for example when vthe hind wheels of the tractor vehicle skid or moveup and down due to the contour'of v 'vide a particularly desirable andeffective the road bed, and it is furthermore exaggei'ated by thesprings. r

2. The point of connection between the above the ground, so that anyside movement of the tractor tends to produce an exagger ated movementof'the trailer.

3. The length of the draft. gearconne'ctionhas usually 'beelishort andconsequently the the draft gear,

For this reason the point of connectionis subject to v.

of the vehicle. I shown as applied to the tractor section of" trailer issensitive to and easily; and 'zad'a versely influenced bythe movement ofthe tractor.; considerable extent the aforesaid Idisadvan-y. ta'ge byproviding a relatively'long -dr aft gear mechanism,,which under normalside sway operating conditions," acts likefia rig-id bar and whichnevertheless is arranged to automatically break a joint at anintermediate point in its length whenever the tractor andtrailer swingaround a curve of predetermined radius, the arrangement being 'such'thatfor a large radius curves, such as are negotiated in operating onordinary roads without making a-turn, the connection remains rigid andacts as a unit while in making a relatively short; turn the. joint willbe brought into action, r s v Therelativelylong zdraft gear of myin'vention is preferably secured to the power -vehicle "ortr'actor atI-apoint nearthe rear ccording my invention I avoid to; a

the clearance "ofth'e vehicle.@Furtherinore- T the draftegear.inechanism is "preferably con nected Sat-the trailer end, 'close. tothe. trailer axle which is as .near the ground as possible.-

.The. details of the tconnectionbetween the sections :of the drawb'arwill be brought out hereinaftei andzit may be generally stated that thej-oi'ntisso arranged as to interlock,

ands-give the effect of-a continuous rigid bar in :a horizontal orsubstantiallyhorizontal plane and is arranged to be released when thetractor section of" the bar is' raised, which; isaccomplished"automatically by meansxof' a suitabl'e cam mechanism, whenthe draw bar swings a certain number of angular degrees to onewside orthe other by'the turning This cam mechanism-while the draw bar, may, ofcourse-,"be applied to the trailer section if desired.

A further object of my invention-is to pro v mechanism forsteeringthetrailer in re sponse to the turning ofthe!tractor. Otherobjects and advantages of my invention will be set forth-hereinafter andI the front end of a trailer which are interconnected by draft andsteering gearmechanisms arranged and constructed in accordance withmyinvention. I I

Figure 2 is a plan view of the apparatus shown in Figure 1 with certainparts broken away and shown in section.

Figure 2" is an enlarged detail view of a portion of the brake actuatingmechanism.

Figure 3 is a front elevation of the trailer of the previous figuresandFigure 41s a rear elevation of the tractor.

Figure 5 is a sectional detail on the line 5+5 of Figure 3 drawn to alarger scale and showing the brake actuating mechanism.

A modified steering mechanism, which also embodies my invention,- isshown in Figure 6. II I Figure 7 is a view corresponding to Figure 3 ofa modified arrangement of the brake actuating mechanism, showing thedrawbar connected-to ,thetrailer at a point near the axle. I

Figure 8 is a modified draw bar equipped with an automatic controladapted to be used with electrically governed or actuated brakes. I I IFigure 9 is a'slight modification of Figure 8 showing a draw baractuatedcontrol for governing either pneumatic or hydraulic brakes or brakemechanisms.- i

Having special reference to Figures 1 to 5 inclusive, 10 designates achassis of a' truck or other tractor. having a rear axle 11,'and wheels12.. The frame 13 is secured to the chassis preferably at'a considerabledistance may belocated at the rear end of the tractor. I

.16 designates the chassis of a trailer having an axle 17 with steeredwheels 18 associated therewith in the usual manner. A draw bar 19comprises a spring-connected telescoping section .20 universallyconnected at 21 to the chassis 16, and a rigid section 22 which isremovably pinned or otherwise connected to thecoupling socket .14.. Thedraw bar may be and preferably will be connected to thetrailer at theaxle or a point near the axleand I have shown a modified arrangement inFigure 7 which may be considered preferable in some cases.

The draw bar sections 20 and 22 are connected by a special joint, 23which is arranged in such manner that, when the parts are insubstantialalignment, they act like a rigid member and when one of thesections is elevated, byreason of the action of the cam bracket,=-asmore fully explained hereinafter,.thejoint is broken, permitting theparts to toggle and occupy the position shown in dotted lines 'inFigures 1 and 2.

The joint 23 comprises a pair of cooperatmember 25 and is provided witha spring 28 which presses the lugs together. The arrangement of parts issuch that in a vertical plane the joint is slightly overset and consequently co'mpressiveforces do not tend to lift the: sections or breakthejoint. j Any-other suitable means for maintaining the desiredarrangement may be utilized insteadof the spring. II

The cam bracket 15 is clearly shownin Figure 4 and is formed with acentral de pression 29 which is sufficiently wide to permit thenecessary swinging of the draw bar sections when the tractor and trailerare rounding a curve or making a turn- The sides of the depression areinclined or curved downwardly toward the bottom so that they act as camsurfaces and elevate the draw bar section 22 when it moves to anyconsiderable extent on either side of the center. I prefer to allow fora small lateral movement in either direction before the cam surfacescome into action. I

The draw bar section may be made intwo parts designated respectively20**- and 20*,

20- being hollow or tubular and providing a socket into which 20extends. The parts telescope and the relative movement is limited by pin30 inslot 31, the spring 32 being within the pivoted section 20 andconnected to both members so that it may act in tension and reduce theshocks at starting. The spring construction may be modified in variousways within the spirit and scope of my invention and the spring may beomitted entirely -if desired. I 1 I As above indicated the wheels 18 aremounted on steering knuckles in the usual established from the pins 36and 38, by

springs 42 and 43 or some other suitable means, to the draw bar section20 i The steering arms constitute a suitable means for carry'ing brakebands or at least carrying a stop for limiting the rotative movement ofthe'bands as hereinafter eX- plained. I

Each is provided with a brake drun144 which in the arrangement shown isinternally acted upon by a brake band or ring 45. The brake band ismounted on a disc 46 having supporting lugs 47 which do not int'eraferewith a limited rotative movement of the band. These lugs are bolted inplace and by removing one bolt may be swung radially inward to permitthe ready'replacement of the brake band. The bra'kei band has lugs 48 atits respective ends to which actuating links 49 and 50 are connected.Thelinks are connectedat their opposite ends to a toggle lever 51, onebeing connectedto anintermediate point in the toggle lever-and the otherto one end of the toggle lever. The opposite end of the toggle" lever isconnected by alink 52 to an actuating lever 53 which is pivotallymounted on the disc 46 at 54 andextends at one end into the path ofmovement ofa primary actuating bell crank lever 55 which is mounted onthe axle '17. The point of cont'actlbetween the levers 55 and 53 isinalignment with the steering axis of the .wheel and consequently thebraking action is transmitted irrespective of the angle to which thewheelsare' turned. The brake arrangement is duplicated for the otherwheel and the two levers 55 are interconnected by links 56, bell cranklevers 57 and links 58 which are joined together over the center of theaxle and to' a vertically acting rod 59.

Thestructure at this point is shown in detail inFigure 2, to whichspecial reference may now be had. -As here shown the rod 59 is enlargedforming a'ball 61 at its 'lower end, which is set into a socket 62formed in a universal bell crank member 63 preferably-of circular form.-The socket'62 is cut away at 62 to provide clearance. The

member 63 is conveniently composed of-two parts that are rigidly securedtogether by bolts 63 orvother suitable means. A horizontal supportingplate 64 is mounted on the axle 17 by spaced'bra'ckets 65and-isperforated at 66 to form an opening through which the rod 59extends.

64*which is suitablyfastened to the under side ofthe sup-porting plate64. Therod is enlarged at 67 to form a shoulder and aspring '68 isinterposed between the'shoulder' thus formed and the plate 64 in suchmanner as to elevate the rod and hold the bell crank member 63 againstthe underside of the plate 64.

'A bolt or adjustable extension69 extends- The bell crank 1 member 63 isseated in an annular abutment 'vious figures? a i The operation '01 themechanism is as folk engage the link and push it bac'kwardly when thedraw bar sections 20 and 20' are forced together by the pushing of thetrailer against the tractor as hereinafter explained; This action causesthe link to swing and to force the bar 72 backwardly which in turn rocksthe bGllvOI'fiH-k member 63, which is restrained against slidingmovements by the ring abutment 64*. This rocking movement will takeplace in thesame-manner and to snbstantially the same extent and"efiiect I substantially thejsameresult irrespective of j the angle towhich the wheels may be turned, the-angle of brakej application beingthus immaterial. a

The bell crank member 63 'when thus rocked'turns about a pivot at its"edge: and pulls downwardly on the rod 59 thus com pressing the lightspring 68. -'Th-i's down-- ward pull actuates the brakes through themechanism above described andin the man ner more fully pointed outhereinafter.

= As soon as the pressure on the rod7-2 ismember a -90.

released the universal-bell crank 63 is reseatedby-the spring 68.

' Referring to Figure 6 the steering mech anism" may be modified" toaccommodate rearwardly extending steering arms such as- 76, the spaceror distancepiece 77 "being substi'tutedior the member 41 of FigureQ andbeing provided wit'h slots 78 which are of suitableshape to" permit thesteering of the'fl wheels when engaged by pins or projections 79 of thearms. The'steering arms are-con;

nected, by springs orot-he'r connections indicated at 80,- to anextension 81 ot the draw bar section 82 which corresponds to the section20.

In this arrangement the draw bar section instead of being connected tothechassis 1 6 of the'trailer is connectedtoithe axle by a gimbalor-other suitable universal joint :indicated at 83.

in Figur-e 7, like parts being designatedby the same reference.character as in thelpre- Assumingthat the tractor 1O is drawing thetrailer uphill or on .arlevelroadg' or under any'conditions, suchth at'the drawbar is under tension, the brakes are released and the draw barsections occupy the position In this arrangement the brake actuating tbar'instead' of being below the draw bar isiabove it as clearlyindicated shown infull lines in Figures 1 and 2.; If

if thetractorslowsup so that the trailer -ati the tractor and trailerstart-down grade, or, v

tempts'to push against the'tractor the draw bar section 20 is pushedinwardlyinto the section 20 with which it' telescopes,vcompresses thespring 82'and, through the ac:

tion of the member 75, actuates the link '73 and produces a bac'kwardpushon the-rod g 72. This rod, as already explained inconnection withthe description of the brake per se, serves to rockthe bell crank member63 about its edge, producing a pull on therod 59 and thus setting thebrakes on the trailer. Anadjustable stop 76 projecting from the steeringarm-76 into the brake drum on the right, or upper side as viewed in thefigure, serves-to limit the travel of the brake equalizer at will.

The application of the brake is dependent upon and determined by theforce with which thetrailer tends to push against the tractor. This isas it should be and the trailer is in consequence governed in responseto the action of the tractor which is;

of course directly responsive to the driver.

In other words, when the driver of the trac tor sets his brakes, thebrakes on the trailer are automatically set to the extent necessary tohold back the trailer under the existing conditions.

The draw bar under the conditions just and such as to prevent whippingor side swaying of vthe trailer relative to the tractor. The sameconditions exist for curves of longradius such. as are encountered in anordinary road, but conditionsare different when a sharp curve or turn isnegotiated.

Assuming that the tractor is turned, as shown in broken lines in Figure2, the draw bar section 22 is forced to one side of the center and.rides up one of the cam sur-- faces of the cam bracket (this cammingaction is purposely arranged so as to not affeet-the draw bar for largeradius turns) so as to raise the section into the broken line positionof Figure 1 and permit the joint to break, allowing the parts to knuckleas shown in broken lines in Figure 2. By this means I secure theadvantages of the long rigid draw bar for'straight-away operationwithout preventing sharp turns.

Furthermore,the arrangement is such that I the trailer will track thetractor, avoiding the possibility of cutting corners.

If, when thedraw bar sections are at an angle as shown in broken linesin Figures 1 and 2 the trailer tends to push against the tractor, thereaction through the draw bar section is transmitted .to actuate thebrake the same as above described for the straight-away operation,attention being 1 particularly directed to the fact that both ways as,for example, electrically or pneumatically.

Figure 8 showsthe'draw bar sections telescoping as before, with yarheostatic con-' troller 84L havingan arm 85 which is connected by a rodor link 86, and a lug 8-7 clamped or otherwise secured to the section 20Arrangement of parts is such that the reactionary movement causing thedraw bar section 20 to telescope, swings the arm 85:

so as to introduce to a greater or less degree electrical energy forapplying the brakes in some suitable manner. I have not shown themagnets or motors for efi'ecting the brake application as their form is"immaterial to my invention, the regulation of the force ofapplication-dependent on the extent of the-overhauling tendency ,orpushingvforce exerted by the trailer being germane to my invention.Instead of the rheostatic controller .84 any suitable -con-.

trolling device may be utilized.

Figure 9 shows a control valve 88 pro vided with an actuating armorstem' 89 instead of the rheostaticcontroller 84, the valve beingconnected by a rod 90 to be actu:

ated inresponse to the telescoping move-- ment of the draw-bar.

,The valve may of course control the source of fluid pressure for theapplication of vthe pneumatic brake-s or the supply of any suitablefluid or liquid.

Attention. is particularly directed to, on important feature ofmyinvention, viz, the shock absorbing effect of the brakes. Itfis evidentthat the automatic application of brakes on the trailer to a varyingdegreev depending on the existing conditions, serve to absorb andprevent shocks between the tractor and the trailer and not only'preventsor minimizes the hammering or pounding of the parts, but also rendersthe use of spring shock absorbers unnecessary. The, spring 32illustrated between the parts of the draw bar is not a shock absorbingspring in the usual sense, it not being relied upon to. take the shocksof the vehicle, It is merely to maintainthe proper relation between theparts when released and may be omitted if desired.

7 It may however be desirable to arrange it to act in tension as alreadypointed out,-

to tend to pull the telescoping parts together and thus to lessen theshocks at starting or when there is a sudden increase in speed of thetractor which makes it tend to pull away from the trailer. All shockswhich would otherwise occur due to the overhauling of the tractor by thetrailer are absorbed in the brakes. v

Various structural modifications may be effected within the spirit andscope of my invention and I intend that only such limi-' tations beimposed as are indicated in the appended claims. i

What I claim is a 1. In a tractor and trailer the combination with adraw bar comprising jointed sections normally in rigid relation butadapted to knuckle when-the vehicle members are rounding a curve ofrelatively short radius, of a brake actuating mechanism adapted torespond to a compressive action whereby the side swaying of the traileris opposed and minimized; I Y

3. The combination with a tractor, of a trailer having brakes and ajointed draw bar connection between the tractor and the trailer, that isnormally interlocked and is operatively connected to actuate the brakesand arranged to be unlocked under-prede termined conditions to preventside sway-1 ing of the trailer.

.4. The combination with a tractor, of a trailer having brakes, and ajointed draw bar connection between the tractor and the trailer, that isnormallyinterlocked and is operatively connected to actuate thebrakesand arranged to be automatically unlocked to act in conjunctiontherewith to prevent side swaying of the trailer.

5.-The combination with a tractor and a trailer having brakes,of anelongated draw bar between said tractor and said trailer comprising aplurality of pivotally connected sections, means for interlocking saidsections undernormal operating conditions, means adapted tocooperatively engage one of said-sections under predetermined conwhetherthe draw bar sections are interlocked or unlocked and knuckled.

In witness whereof I have hereunto set my hand this 28th day of May,1919.

E. v. LAWRENCE.

